JP4807976B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

    The present invention relates to a pneumatic tire in which a belt reinforcing layer configured by spirally winding a ribbon-like body on which a reinforcing element is covered with a rubber is overlapped on a belt layer and a method for manufacturing the same.

As a conventional pneumatic tire and a manufacturing method thereof, for example, those described in Patent Document 1 below are known.
JP-A-6-183207

  This is a slant belt in which a carcass layer extending in a toroidal shape between a pair of bead cores and a plurality of reinforcing cords which are disposed radially outside the carcass layer and slant with respect to the tire equator are embedded inside A corrugated belt layer formed by spirally winding a rubberized tape, which is disposed so as to overlap the outer side in the radial direction of the inclined belt layer, and a plurality of corrugated steel cords covered with rubber, The inclined belt layer and the tread disposed radially outside the wavy belt layer.

  And in this, each of the winding start portion and the winding end portion of the rubberized tape is positioned inward in the width direction from the side edge of the corrugated belt layer, so that the belt reinforcing layer has a width direction from the side edge. While providing the folding | turning part turned back inside, when winding the said rubber | gum drawing tape helically, it is set as the same winding pitch (width direction feed amount) in any position of the width direction.

    However, in such a conventional pneumatic tire and a method for manufacturing the same, when the rubberized tape is wound spirally, the same winding pitch is set at any position in the width direction. As shown in FIGS. 8 and 9, the belt reinforcing layer 10 has a wide area (three layers) where the number 14 of the rubberized tape 13 is laminated at the both end portions 11 in the width direction than the central portion 12 in the width direction (hatching in FIG. 9). As a result, there has been a problem that the diameter growth of the tread portion becomes uneven during internal pressure filling and high speed running.

  An object of the present invention is to provide a pneumatic tire capable of uniformizing the diameter growth of the tread portion during internal pressure filling or high speed running, and a method for manufacturing the same.

The purpose of this is, firstly, a carcass layer extending in a toroidal shape between a pair of bead cores, and a plurality of reinforcements disposed radially outside the carcass layer and inclined with respect to the tire equator S inside. A belt layer in which a cord is embedded, and a belt reinforcing layer which is arranged to overlap the belt layer, and is formed by spirally winding a ribbon-like body coated with a plurality of non-stretchable reinforcing elements parallel to each other. And a tread disposed on the outer side in the radial direction of the belt layer and the belt reinforcing layer, and the belt reinforcing layer is provided with a folded portion that is turned back from the outer ends in the width direction toward the inner side in the width direction. In the pneumatic tire, the winding pitch of the ribbon-like body at both ends in the width direction of the belt reinforcing layer is made larger than the winding pitch of the ribbon-like body at the center portion in the width direction. Door can be,

Second, both ends in the width direction are folded around the pair of bead cores and filled with internal pressure, and are inclined with respect to the tire equator S on the inside in the radial direction outside the carcass layer deformed in a substantially toroidal shape. A belt layer in which a plurality of reinforcing cords are embedded, and a ribbon-like body covered with a rubber covering a plurality of non-stretchable reinforcing elements parallel to each other, are wound spirally, from both ends in the width direction to the inside in the width direction A pneumatic tire comprising: a belt reinforcing layer having a folded portion folded back; a step of forming a raw tire by stacking and arranging treads; and a step of vulcanizing the raw tire to form a pneumatic tire. In the manufacturing method, when the belt reinforcing layer is formed, the winding pitch of the ribbon-like body at both widthwise end portions of the belt reinforcing layer is set larger than the winding pitch of the ribbon-like body at the widthwise central portion. By the production method of the pneumatic tire, it is possible to achieve.

In this invention, when forming a belt reinforcing layer having a folded portion by spirally winding a ribbon-like body coated with a plurality of non-stretchable reinforcing elements, at both ends in the width direction of the belt reinforcing layer. Since the winding pitch of the ribbon-shaped body is larger than the winding pitch of the ribbon-shaped body in the center portion in the width direction, the number of ribbon-shaped bodies stacked is larger than the center portion in the width direction that occurs at both widthwise ends of the belt reinforcing layer The portion becomes narrower than before, and as a result, the diameter growth of the tread portion at the time of internal pressure filling and high speed running is made uniform.

According to the second aspect of the present invention, it is possible to reduce a region where the ribbon-like body does not exist at both ends in the width direction of the belt reinforcing layer, while sufficiently reducing a portion where the number of ribbon-like bodies as described above is large. Can be narrowed.
Furthermore, if comprised as described in Claim 3, it can fully narrow a site | part with many laminated | stacked ribbon-shaped bodies, suppressing the situation where the site | part with a low winding density of a ribbon-shaped body becomes large. .

According to the fourth aspect of the present invention, the longitudinal direction (circumferential direction) during vulcanization of the reinforcing element, that is, the diameter of the belt reinforcing layer is allowed to be increased, and the production of the pneumatic tire is facilitated. Become.
Furthermore, if comprised as described in Claim 5, the gauge in the center part of the width direction of the belt reinforcement layer formed with the ribbon-like body can be made substantially uniform.
According to the sixth aspect of the present invention, the diameter growth of the tread portion at the time of internal pressure filling and high speed running can be suppressed almost uniformly and effectively while suppressing separation at the end of the belt reinforcing layer. Can do.

Embodiments of the present invention will be described below with reference to the drawings.
1 and 2, reference numeral 21 denotes a flat heavy-duty pneumatic radial tire mounted on a truck, a bus, etc., and this pneumatic tire 21 has a pair of bead portions 23, and each bead portion 23 is paired with each other. Eggplants (here, a pair, but a plurality of pairs) bead cores 22 are embedded. The pneumatic tire 21 includes a sidewall portion 24 extending from the bead portion 23 toward the outside in the substantially radial direction, and a substantially cylindrical tread portion 25 for connecting the radially outer ends of the sidewall portions 24 to each other. And further.

  The pneumatic tire 21 has a carcass layer 28 that extends between the bead cores 22 in a toroidal shape and reinforces the sidewall portions 24 and the tread portions 25. Both end portions of the carcass layer 28 surround the bead cores 22. It is folded back from the axially inner side toward the axially outer side. The carcass layer 28 is composed of at least one carcass ply 29 here, and the carcass ply 29 intersects the tire equator S at a cord angle of 70 to 90 degrees, that is, substantially. A large number of non-stretchable reinforcing cords 30 such as steel cords extending in the radial direction (the meridian direction) are embedded. A chafer 31 reinforced with, for example, a steel cord is disposed around the carcass layer 28 in the bead portion 23.

34 is a belt layer that is disposed radially outside the carcass layer 28 and extends from one tread end to the other tread end. The belt layer 34 has at least two (here, two) belt plies. Each belt ply 35 has a plurality of non-stretchable parallel reinforcing cords 36 made of, for example, steel or aromatic polyamide , and a large number of them are embedded in the belt ply 35. Yes. The reinforcing cords 36 embedded in the belt plies 35 are inclined at an angle of 40 to 70 degrees with respect to the tire equator S in order to reduce circumferential shear strain with the belt reinforcing layer described later. The at least two belt plies 35 are inclined in opposite directions and intersect each other. Reference numeral 38 denotes a tread disposed on the outer side in the radial direction of the carcass layer 28 and the belt layer 34, and reference numeral 39 denotes a side tread disposed on the outer side in the axial direction of the carcass layer 28.

  41 is a belt reinforcing layer arranged radially outside the carcass layer 28, more specifically between the carcass layer 28 and the belt layer 34 so as to overlap the belt layer 34, and having a width narrower than the widest belt ply 35; The belt reinforcing layer 41 is composed of at least one reinforcing ply 42 which is laminated in the radial direction here. Each reinforcing ply 42 has a substantially non-stretchable reinforcing element 43 extending in the circumferential direction and made of steel, aromatic polyamide or the like, and the reinforcing element 43 is made of a stranded wire (cord) or a monofilament. At the same time, a large number of lines appear on the meridional section of each reinforced ply 42.

  Here, the belt reinforcement layer 41 is disposed between the carcass layer 28 and the belt layer 34, while suppressing the separation at the end of the belt reinforcement layer 41, the diameter of the tread portion 25 during internal pressure filling and high speed running This is because the belt reinforcing layer 41 may be disposed between the belt layer 34 and the tread 38 to suppress the growth substantially uniformly and effectively. Each reinforced ply 42 has folded portions 49 and 50 that are folded back inward in the width direction from both outer ends 47 and 48 in the width direction, and the folded portion 49 on one side in the width direction corresponds to each reinforced ply 42. The folded portion 50 on the radially inner side, that is, on the carcass layer 28 side, is folded on the other side in the radial direction of each reinforcing ply 42, that is, on the belt layer 34 side.

  If the folded portions 49 and 50 are provided in the reinforcing plies 42 as described above, the cut ends of the reinforcing elements 43 embedded in the reinforcing plies 42 (the inner ends of the folded portions 49 and 50 are located). The start end and the end end) are located away from both outer ends 47 and 48 in the width direction of the reinforcing ply 42 where a large shear strain is generated. As a result, the separation at the both outer ends 47 and 48 in the width direction is effective. Is suppressed.

The reinforcing ply 42 having the folded portions 49 and 50 as described above is a ribbon-like body in which a plurality of parallel, in this case, a small number of reinforcing elements 43 are arranged and covered with rubber, and is first on one side in the width direction. After forming the folded portion 49 on one side in the width direction by spirally winding from the position to the outer side 47 in the width direction outward in the width direction, the width direction from the outer end 47 in the width direction toward the other side in the width direction The main body 52 is formed by spirally winding up to the outer end 48, and then the other end in the width direction is folded by spirally winding from the outer end 48 in the width direction toward one side in the width direction. Part 50 is formed and molded.

  Here, when spirally winding the ribbon-shaped body described above, assuming that the winding pitch (width direction feed amount) is the same at any position in the width direction, as shown in FIGS. Over the wide range (the range indicated by hatching in FIG. 9) of the portion 14 in which the number of layers of the rubberized tape 13 (three layers) is larger than the widthwise central portion 12 (two layers) at both widthwise end portions 11 of the layer 10 As a result, the diameter growth of the tread portion at the time of internal pressure filling or high speed running becomes non-uniform.

  Therefore, in this embodiment, as shown in FIGS. 3 and 4, when the belt reinforcing layer 41 (reinforced ply 42) is formed by spiral winding of the ribbon-like body 55, both end portions in the width direction of the belt reinforcing layer 41 are used. The winding pitch P of the ribbon-like body 55 in 53 is made larger than the winding pitch Q of the ribbon-like body 55 in the central portion 54 in the width direction. As a result, a portion 56 (a three-layer portion shown by hatching in FIG. 4) in which the number of ribbon-like bodies 55 is larger than that in the width direction center portion 54 generated at the width direction both end portions 53 of the belt reinforcing layer 41. As a result, the diameter of the tread portion 25 can be made uniform during filling with internal pressure or during high speed running.

  Here, the winding pitch P, which is the large ribbon-like body 55, is preferably in the range of 1.3 to 2.0 times the small winding pitch Q. The reason is that if the value of P / Q is less than 1.3, the portion 56 (three-layer portion) where the number of ribbon-like bodies 55 as described above is large cannot be made sufficiently narrow, while 2.0 Exceeds the width F, the region F where the ribbon-like body 55 does not exist becomes wide at both ends 53 in the width direction of the belt reinforcing layer 41 (reinforcing ply 42). This is because the portion 56 (hatched portion) where the number of stacked ribbon-like bodies 55 as described above is large can be made sufficiently narrow while reducing the region F where the ribbon-like bodies 55 do not exist at both ends 53 in the direction. .

  Further, the widths of the folded portions 49 and 50 described above are J, the width of the ribbon-like body 55 is K, the value obtained by subtracting the width K from the width J is M, and the width direction end portions 53 where the winding pitch P is large. When the width is U, the width U is preferably in the range of 1.0 to 2.5 times the value M. The reason is that if the U / M value is less than 1.0, the portion 56 where the number of laminated layers of the ribbon-like body 55 is large cannot be sufficiently narrowed, while the U / M value exceeds 2.5. The both ends 53 in the width direction where the winding density of the ribbon-like body 55 is low are widened (the central part 54 in the width direction where the winding pitch Q is small are narrowed), and the diameter growth of the tread portion 25 is sufficiently suppressed. However, within the above-mentioned range, the portion 56 where the number of laminations of the ribbon-like body 55 is large is sufficiently narrowed while suppressing the situation where the portion where the winding density of the ribbon-like body 55 is low becomes wide. Because it can.

  Further, the reinforcing element 43 embedded in the ribbon-like body 55 described above is, in this embodiment, a wavy or zigzag shape in a plane parallel to the front and back surfaces of the ribbon-like body 55, for example, a square wave, a triangular wave, The sine wave is bent with the same amplitude and arranged in the same phase, that is, so that the top and bottom of the reinforcing element 43 in the adjacent ribbon-like body 55 are located on the same straight line extending in the width direction. When the reinforcing element 43 is bent in a wave shape or a zigzag shape as described above, the reinforcing element 43 extending substantially in the circumferential direction extends in the longitudinal direction (circumferential direction) during vulcanization, that is, the diameter of the belt reinforcing layer 41 increases. Is permitted, and the manufacture of the pneumatic tire 21 is facilitated. The reinforcing element 43 may extend linearly without undulation. In this case, a reinforcing element having a large initial elongation is used.

  Here, when the reinforcing element 43 in the ribbon-like body 55 is bent in a wave shape or zigzag shape as described above, the winding pitch Q of the ribbon-like body 55 in the central portion 54 in the width direction of the belt reinforcing layer 41 is As shown in FIGS. 3, 4, and 5, it is preferable to set the ribbon-like body 55 to approximately half the width K. This is because when the winding pitch Q is considerably larger than half of the width K, for example, about 3/4, the one-layer portion and the two-layer portion are arranged in the width direction at the central portion 54 in the width direction of the formed reinforcing ply 42. As described above, the gauge at the central portion 54 in the width direction of the belt reinforcing layer 41 (reinforced ply 42) formed by the ribbon-like body 55 can be made almost uniform (two layers). It is.

    Next, to manufacture the pneumatic tire 21 as described above, first, a belt-like carcass layer 28 is supplied to a rotating forming drum (not shown) capable of expanding and contracting, and a cylinder is formed around the forming drum. The bead cores 22 are respectively set at predetermined positions on both ends in the axial direction on the outside of the carcass layer 28, and then both ends in the width direction of the carcass layer 28 positioned on the outside in the axial direction from the bead core 22 are bladdered. The belt-shaped side tread 39 is then fed to the forming drum, and is attached to the outside of both ends in the axial direction of the carcass layer 28 folded as described above. Mold 57.

  The cylindrical tire intermediate body 57 thus molded is carried from the molding drum to the molding drum 59 shown in FIG. 6 by a conveying means (not shown) and fitted to the outside thereof. The bead receiver 60 of the forming drum 59 is positioned inside the bead core 22 of the intermediate body 57 in the radial direction. Next, the diameter of the bead receiver 60 is increased, and the bead core 22 of the tire intermediate body 57 is firmly gripped from the inner side in the radial direction via the carcass layer 28.

  At this time, while rotating the band forming drum 63 capable of expanding and contracting as shown in FIG. 7, the ribbon-shaped body 55 is supplied to the outer periphery of the band forming drum 63 while moving in the axial direction of the band forming drum 63. A ribbon-like body 55 is spirally wound around the drum 63 to form the reinforcing ply 42. Specifically, first, after forming the folded portion 49 on one side in the width direction by spirally winding from a position on one side in the width direction to the outer end 47 in the width direction outward in the width direction, the outer end in the width direction A main body 52 is formed by winding a number of times spirally from 47 to the width direction outer end 48 toward the other side in the width direction, and then spirally from the width direction outer end 48 to one side in the width direction. By winding, the folded portion 50 on the other side in the width direction is formed, and the reinforcing ply 42 is formed.

  This will be described with reference to FIGS. 3 and 4. First, the first ribbon-like body 55-1 is wound at a large winding pitch P to form the folded portion 49, and in the middle of the winding. The direction of movement is reversed from the outer side in the width direction to the inner side in the width direction to form the outer end 47 in the width direction, and then the ribbon-like body 55-2 of the second roll is increased toward the inner side in the width direction. The both ends 53 in the width direction are formed by both the ribbon-shaped body 55-2 of the second volume and the ribbon-shaped body 55-1 of the first volume.

  Next, the center part 54 in the width direction is formed by winding the ribbon-like bodies 55-3, 55-4, 55-5,. Regarding the other end in the width direction of the reinforced ply 42, the width direction both ends 53 are formed by setting the winding pitch P to be the second winding from the final winding and the winding pitch P in the final winding. In the middle of winding, the width direction outer end 48 and the folded portion 50 are formed by reversing the moving direction from the width direction outer side to the width direction inner side.

  As described above, when forming both ends 53 in the width direction of the reinforcing ply 42 including the folded portions 49 and 50 by spiral winding of the ribbon-like body 55, the winding pitch P of the ribbon-like body 55 at the both ends 53 in the width direction. Is larger than the winding pitch Q of the ribbon-like body 55 in the width-direction central portion 54, the portion where the number of ribbon-like bodies 55 is larger than the width-direction central portion 54 generated at the width-direction both ends 53 of the reinforcing ply 42. 56 (shown by hatching in FIG. 4 in a three-layer region) can be made narrower than before. Then, two such reinforcing plies 42 are formed to form a cylindrical belt reinforcing layer 41.

  Next, two belt-like belt plies 35 are supplied around the band forming drum 63 one after another and are stuck to the outside in the radial direction of the belt reinforcing layer 41 to form the cylindrical belt layer 34. Thereafter, a belt-shaped tread 38 having a width wider than that of the belt layer 34 is supplied to the outer side in the radial direction of the belt layer 34 and is attached in a cylindrical shape. Accordingly, a cylindrical belt tread band 65 including the belt reinforcing layer 41, the belt layer 34, and the tread 38 is formed outside the band forming drum 63.

  Next, the tire intermediate body 57 (carcass layer 28) is filled with internal pressure while the bead receivers 60 are brought close to each other, and the cylindrical tire intermediate body 57 is gradually deformed so as to have a substantially toroidal shape. At this time, the belt tread band 65 formed by the band forming drum 63 is conveyed by a conveying means (not shown), and is fitted and arranged on the radially outer side of the tire intermediate body 57 as shown in FIG. As a result, the outer peripheral surface in the axial center of the tire intermediate 57 is in close contact with the inner peripheral surface of the belt reinforcing layer 41.

  Next, the forming drum 59 is rotated, and a stitching roll (not shown) is pressed against the outer surface of the tread 38 while moving in the axial direction, and the laminated belt reinforcing layer 41, belt layer 34, and tread 38 are tired. Affixed to the outside of the intermediate body 57 to form a green tire. Thereafter, the green tire is carried into a vulcanizing mold and vulcanized to obtain a pneumatic tire 21.

    In the above-described embodiment, one ribbon-like body 55 is spirally wound from a position on one side in the width direction to the outer end 47 in the width direction to form the folded portion 49, and then spiraled to the outer end 48 in the width direction. The main body 52 is formed by winding, and then the reinforcing ply 42 is formed by spirally winding toward one side in the width direction to form the folded portion 50. In the present invention, the two ribbon-like bodies are formed. You may make it shape | mold the reinforcement | strengthening ply in which the folding | turning part was provided by winding spirally from the width direction center to the width direction outer end, and then winding spirally toward the width direction inner side.

  In the above-described embodiment, the belt reinforcing layer 41 (reinforcing ply 42) is formed by spirally winding the ribbon-like body 55 around the band forming drum 63. Alternatively, the belt reinforcing layer (reinforced ply) may be formed by directly spirally winding the carcass layer 28 (tire intermediate body 57) having a substantially toroidal shape on the outer side in the radial direction.

  The present invention can be applied to the industrial field of pneumatic tires in which a belt reinforcing layer is superposed on a belt layer.

1 is a meridian cross-sectional view of a pneumatic tire showing an embodiment of the present invention. It is the partially broken top view. It is meridian sectional drawing which shows the width direction one end part of a reinforcement ply. It is an expanded view which shows the width direction one end part of a reinforcement ply. It is a partial top view of the width direction center part of a reinforcement ply. It is front sectional drawing which shows the intermediate stage of manufacture of a pneumatic tire. It is a front view which shows the state which affixes a ribbon-shaped body on a band shaping | molding drum. It is meridian sectional drawing which shows the width direction one end part of the reinforcement ply in a prior art. It is an expanded view which shows the width direction one end part of the reinforcement ply in a prior art.

21 ... Pneumatic tire 22 ... Bead core
28 ... Carcass layer 34 ... Belt layer
36 ... Reinforcement cord 38 ... Tread
41 ... belt reinforcing layer 43 ... reinforcing element
49, 50 ... folded part 53 ... both ends in the width direction
54 ... Center in width direction 55 ... Ribbon

Claims (7)

A carcass layer extending in a toroidal shape between a pair of bead cores, a belt layer disposed on the radially outer side of the carcass layer and embedded with a plurality of reinforcing cords inclined with respect to the tire equator S; A belt reinforcing layer formed by spirally winding a ribbon-like body, which is arranged to overlap the belt layer and covered with a plurality of non-stretchable reinforcing elements parallel to each other, and the belt layer and the belt reinforcing layer A pneumatic tire including a tread disposed radially outward, wherein the belt reinforcing layer is provided with a folded portion that is turned back from the outer ends in the width direction toward the inner side in the width direction. A pneumatic tire characterized in that the winding pitch of the ribbon-like body in the portion is larger than the winding pitch of the ribbon-like body in the center portion in the width direction.     The pneumatic tire according to claim 1, wherein the large winding pitch is within a range of 1.3 to 2.0 times the small winding pitch.     When the value obtained by subtracting the width of the ribbon-like body from the width of the folded portion is defined as M, the width at both ends in the width direction where the winding pitch is large is set within a range of 1.0 to 2.5 times the subtracted value M. The pneumatic tire according to claim 1 or 2.     The pneumatic tire according to claim 1, wherein the reinforcing element is bent in a wave shape or a zigzag shape in a ribbon-like body.     The pneumatic tire according to claim 4, wherein the winding pitch of the ribbon-like body at the center portion in the width direction of the belt reinforcing layer is approximately half the ribbon-like body width.     The pneumatic tire according to claim 1, wherein the belt reinforcing layer is disposed between the carcass layer and the belt layer. A plurality of reinforcements that are inclined with respect to the tire equator S on the outside in the radial direction of the carcass layer deformed in a substantially toroidal shape by folding both ends in the width direction around a pair of bead cores and being filled with internal pressure A belt layer in which cords are embedded, and a ribbon-like body coated with a plurality of non-stretchable reinforcing elements that are parallel to each other, are wound spirally and folded back inward in the width direction from both ends in the width direction. In a method for manufacturing a pneumatic tire, comprising: a belt reinforcing layer having a folded portion; a step of stacking and arranging a tread to form a green tire; and a step of vulcanizing the green tire to form a pneumatic tire. When forming the belt reinforcing layer, the winding pitch of the ribbon-like body at both ends in the width direction of the belt reinforcing layer is set larger than the winding pitch of the ribbon-like body at the center in the width direction. The pneumatic tire manufacturing method to be.

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